715 combine diesel engine into 806?

Rusty R

New User
I have an 806 gas that is getting tired, uses oil. Have a chance to buy a 715 combine with a german diesel in it cheap. Will that work out? Combine is a hydrostat if that matters.
 
You have to go to a salvage yard and find front and rear motor plates flywheel and a few other parts off a 756 german or 826 german to make it work.
 
If I was to do this, is the german engine the better choice of the two engines? I still do some farming with the 806.
 
You are also going to have to deal with the difference in the electrical and fuel systems between a gas and a diesel. This can be done but it is going to take a lot of work and backyard engineering. It has been discussed several different times on this board and the consensus is usually - if you want a diesel then go buy a diesel. Otherwise keep it as a gas.
 

Gas to diesel, it's worth it if the cost of the engine, parts, and labor is less than the cost of rebuilding the gas engine, and there's nothing wrong with the diesel engine.

You will recoup a bunch of money though fuel savings too, but how much depends on how much you use the tractor. For Dad's 756, the gas bill went down by 1200 gallons, and the diesel bill only went up by 300 in the first year after we had a D360 installed. Basically, the conversion paid for itself within 2 years.

There are a LOT of small issues to deal with in the conversion.

First off, the diesel's rear engine plate is about 3 times thicker than the gas engine rear plate. To compensate, the frame rails on a diesel are shorter. To make it an easy bolt-up, you need to get diesel frame rails. We kept the gas frame rails on the 756, and it ended up about 1-1/2" longer, so the hood doesn't fit anymore, the power steering lines were too short, and countless other things were thrown off. We lucked out and found a mechanic who wanted to do it just for the challenge, and he had a blast figuring out how to meet all the challenges. Some of his solutions were a little cob-jobby, but Dad fixed them all eventually, and made extensions for the hood.

One biggie was that the bottom coolant outlets on the engine and radiator were on opposite sides. The mechanic had his son weld up a custom radiator pipe to cross over, rather than purchase the correct radiator at $500+.
 

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